1. Field of the Invention
This invention generally relates to an endotracheal tube, and more particularly, to an endotracheal tube having an inflatable cuff that forms a tapered collection pocket when inflated for urging the collection of secretions and a rail system adapted for securely and safely guiding a suction catheter along the tube for facilitating the aspiration of secretions pooled in the cuff pocket and the area above the trachea.
2. Description of Related Art
A well known problem with endotracheal tubes is the buildup of excessive oropharyngeal and gastroesophageal secretions above the cuff of the tube in the trachea and subglottic area when a patient is intubated. Endotracheal intubation is used for mechanically ventilating a patient's lungs when the patient cannot breathe normally and/or for introducing anesthetic gases into the lungs. However, the intubated patient is almost always placed at risk by the accumulation of pooled secretions between the inflated cuff and oral pharyngeal area. The accumulation and stagnation of oral secretions breeds infectious organisms that can result in pneumonia. The accumulated secretions eventually leak into the patient's lungs or find their way into the lungs when the endotracheal cuff is deflated for removal or when a patient is turned and, or coughs. Conventional procedures for preventing pneumonia associated with tracheal intubation require confirmation that secretions are cleared from above the tube cuff before deflating the cuff and removing the tube. Some endotracheal tubes have a dorsal lumen formed in the walls of the tube above the cuff for draining accumulated secretions by suction. However, there are no known recommendations for routinely and effectively using an endotracheal tube with a dorsal lumen. This is in part due to the fact that the dorsal lumen can become easily occluded, which would require complete removal of the tube. Thus, intubated patients are always at risk of developing bronchitis, pneumonia and other life-threatening infections because of pooled secretions entering the trachea and lungs.
Up until 1936, pneumonia was the leading cause of death in the United States. Even with all the modern advances in medical technology and antibiotic therapy, pneumonia is currently the sixth leading cause of death in the U.S. (CDC, 1997). Nosocomial (hospital-acquired) pneumonia is a frequent complication in mechanically-assisted ventilator patients, according to a national, multi-million dollar, multi-center research study by the Centers for Disease Control (1997), pneumonia is the second most common nosocomial infection in the United States and is associated with substantial morbidity and mortality. The CDC further states that because intubation and mechanical ventilation alter first-line patient defenses, they greatly increase the risk for nosocomial bacterial pneumonia. The risk for pneumonia is increased by the direct access of bacteria to the lower respiratory tract, which often occurs because of leakage around the endotracheal cuff, thus enabling pooled secretions above the cuff to enter the trachea. According to Marino (1998), the aspiration of mouth secretions into the upper airways is the inciting event in most cases of pneumonia. An average of 1 billion bacteria are found in each milliliter of saliva, so aspirating only a micro-liters of saliva can introduce large numbers of bacteria into the airways.
According to Lewis et al (1997), endotracheal intubation interferes with the normal cough reflex and the mucociliary escalator mechanism. Decreased consciousness depresses the cough and epiglottal reflexes, which may allow aspiration of oropharyngeal contents into the lungs. It also bypasses the upper airways in which filtration and humidification of air normally take place (622).
Nosocomial pneumonia is a complication that not only increases mortality/morbidity rates, but also causes substantial increases in financial costs due to significant increases in length of stays (LOS) in high tech, intensive-care units. A one-two week increase in a patient's LOS in an ICU is a very significant fiscal consideration and hardship, which can cost $3,500.00 to $5,000.00 a day.
Conventional endotracheal tubes contribute to the problems associated with pooled secretions in the trachea area. The conventional endotracheal tube has an inflatable cuff that blocks the passageway and allows secretions to accumulate above the cuff. The tube has an inflation lumen that extends between a proximal end and a distal end for inflating the cuff. The inflatable cuff is joined to the tube above the distal end to prevent the passage of fluids and gases to and from the lungs when inflated. The cuff is inflated so that it engages the trachea wall thereby providing a proper seal. However, as the trachea is sealed, oral secretions tend to pool or build up above the cuff. If these secretions could be safely and conveniently aspirated the foregoing health concerns could be eliminated or greatly reduced. However, costs and practical constraints have prevented the adoption of a reliable, cost effective endotracheal and aspiration system.
In addition to the foregoing, conventional endotracheal tubes are limited in their use, difficult to monitor and provide methods of treatment but no information. As endotracheal tubes invade the body, it would be beneficial and helpful if it could provide useful information. For instance, if an endotracheal tube could be designed to also monitor a patient's temperature it would provide important medical information to a practitioner.
Moreover, an endotracheal tube that was able to provide a means for early detection of tissue hypoperfusion, such as structure for measuring oropharyngeal PCO2, would provide an additional benefit over conventional tubes. An eleveation in oropharyngeal PCO2 is an early warning signal for tissue hypofusion. Limiting the risk of organ damage resulting from tissue hypoxia is one of the biggest challenges in patient care. Because tissue perfusion and oxygenation help maintain organ vitality, tissue perfusion is literally a matter of life and death. A noninvasive sublingual system known in the prior art and sold under the trademark CapnoProbe measures PCO2 through fiber optic technology. Such devices comprise additional required equipment and can be expensive. An endotracheal tube having structure for continuously measuring oropharyngeal PCO2 could provide a more economical device and more convenient option that facilitates taking continuous measurements and would be well received.
Endotracheal tubes are not new in the art and several have provided structure for draining fluid from the lungs and/or insufflating the lungs with oxygen or other gases. Other known devices have addressed the problem of removing pooled secretions through the cuff opening 98 from the upper tracheal area, but have failed to solve the problem as contemplated by the instant invention. Many of the endotracheal tubes known have a suction lumen that is integrally formed along or through the wall of the endotracheal tube. This design increases the thickness of the tube and calls for the entire endotracheal tube to be discarded when the suction lumen becomes damaged or permanently occluded or is the wrong size for the required aspiration. Designs that have a separate but permanently attached catheter can rupture the trachea wall. These endotracheal tubes and similar designs have edges that could scrape and cause trauma to the tracheal passageway.
The prior art devices known are disclosed in the following patents. U.S. Pat. No. 5,143,062, issued to Peckham, discloses an endotracheal tube comprising a double lumen through which air may be circulated, creating an indirect gentle suction through a suction eye communicating with the distal ends of the lumens, and located at a position proximal to the inflation cuff. This design, however, does not provide adequate suction necessary for aspirating secretions and is easily occluded. The Peckham device, is not practical for convenient hospital use and appears to be unsuitably thick. U.S. Pat. No. 4,305,392, issued to Chester, discloses an inflatable cuff type endotracheal tube having a suction chamber adjacent to the upper-side of the cuff. U.S. Pat. No. 4,334,534, issued to Ozaki, discloses an emergency airway tube for use in resuscitation of non-breathing patients by inserting the tube through the mouth until it randomly lodges either in the trachea or the esophagus. U.S. Pat. No. 4,584,998, issued to McGrail, discloses an endotracheal tube including up to three lumens, in addition to the primary lumen, which serves various functions to provide versatility in the treatment of patients. One lumen is used for inflating the cuff once the tube has been placed in the trachea; another is used to deliver oxygen or other gases by constant insufflation, intermittent jet ventilation or high frequency ventilation; and the third is used for monitoring and irrigation. U.S. Pat. No. 4,607,635, issued to Heyden, discloses an endotracheal tube with an elongated passage along its length. The tube has a plurality of ports along the passage to provide for removal of secretions that accumulate outside the tube and between the tube. U.S. Pat. No. 4,632,108, issued to Geil, discloses a flexible tubular assembly having a lumen for removing smoke generated during lazer surgery. U.S. Pat. No. 4,637,389, issued to Heyden, discloses a tracheal tube providing an expansible channel along its length, which normally maintains a generally concealed attitude within the trachael tube wall and adapts by expansion for the insertion of a suction catheter. U.S. Pat. No. 4,688,568, issued to Frass, discloses a tube that has an airway for sole esophageal obturator or endotracheal and esophageal-obturator ventilation and an inflatable cuff in the area of the tip of the airway and air-outlets in the area of the pharynx. U.S. Pat. No. 4,762,125, issued to Leiman, discloses a balloon-tipped suction catheter that embodies an elongated tube with a cannula extending along the elongated tube. U.S. Pat. No. 4,840,173, issued to Porter, III, discloses an endotracheal tube having dual passages provided by the merging of a ventilation tube and a suction tube. U.S. Pat. No. 5,520,175, issued to Fry, discloses an endotracheal tube with an inflatable cuff having a convex shaped superior surface forming a collection basin to facilitate accurate suctioning while tube is in position.
The above noted patent references fail to adequately address many important issues. Conventional endotracheal and tracheal tubes lack the ability to suction both oropharyngeal and gastroesophageal secretions, even when a patient is turned according to nationally instituted decubitus prevention protocols. They fail to provide a suction catheter or lumen that is replaceable while a patient is intubated. The prior art endotracheal tube designs do not adequately accommodate chlorhexidine rinses to prevent colonization of bacteria around the trachea area above the cuff and can trigger cough reflexes, which allow secretions and fluids to flow past the cuff. Conventional designs also fail to counter torquing of the cuff balloon that can occur when a patient coughs.
The patent references found fail to provide an endotracheal tube that adequately addresses the foregoing issues or that has a suction catheter or lumen that is replaceable while a patient is intubated, adapts to the contours of the tube and contains secretions even when a patient is turned. As the background devices fail to disclose an endotracheal tube and suction catheter system having these structural characteristics, the need for such a device is apparent. The instant invention addresses this by providing an endotracheal tube and suction catheter system comprising a replaceable suction/aspiration catheter, guide rail system and collection pocket that is designed to hold secretions even when a patient is turned.